Tangled Colony probably works best in multicolor decks where you have access to some direct damage spells, or at least spells that force creatures of your choice to fight.
In such decks you are essentially taking a tiny consistency hit on your mana base for the chance to eek out a few free damage in floods and late game situations
Once per turn: You can target 1 card you control and 1 Level 4 or lower monster in your GY
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if successful, how do I settle the card effects
There are other variations of this card, but this particular printing can run someone about $362 on TCGplayer and doesn't have any recent sales on eBay, though there are some currently active listings of wildly varying prices